Continuous shear resistant timber girder

ABSTRACT

A continuous shear timber girder of the class employed in framing a building structure is constructed from dimension timber and sets of plywood webs combined together in adhesively bonded relationship. A unique combination of components provides a timber girder of extended length having a required high degree of bending and shear resistance strength occurring in substantially balanced relationship all along the extended beam length. At intervals along the girder in zones of high shear stress, there are further provided access openings through which pipes, electrical conduits and other service lines may be located. The high shear forces are safely contained and transmitted by connected sets of plywood webs. Where the plywood web system is interrupted at the above indicated service access openings, vertical studs and diagonal studs are interconnected with the separated sets of web parts and maintain shear resistance continuity within limits dictated by the bending strength of the girder.

United States Patent [191 Hunt et a].

[4 1 Jan. 21, 1975 CONTINUOUS SHEAR RESISTANT TIMBER GIRDER [75] Inventors: Robert Hunt, Barrington, R.I.; Paul S. Crandall, Concord, Mass.

[73] Assignee: Gerrity Company, Inc., Boston,,

Mass.

22 Filed: Dec. 19, 1973 21 Appl. No.: 425,964

Primary Examiner-Ernest R. Purser Assistant Examiner-H. E. Raduazo Attorney, Agent, or Firm-Munroe l-l. Hamilton [57] ABSTRACT A continuous shear timber girder of the class employed in framing a building structure is constructed from dimension timber and sets of plywood webs combined together in adhesively bonded relationship. A unique combination of components provides a timber girder of extended length having a required high degree of bending and shear resistance strength occurring in substantially balanced relationship all along the extended beam length. At intervals along the girder in zones of high shear stress, there are further provided access openings through which pipes, electrical conduits and other service lines may be located. The high shear forces are safely contained and transmitted by connected sets of plywood webs. Where the plywood web system is interrupted at the above indicated service access openings, vertical studs and diagonal studs are interconnected with the separated sets of web parts and maintain shear resistance continuity within limits dictated by the bending strength of the girder.

7 Claims, 11 Drawing Figures PATENTED JANZ] I975 SHEET 10F 2 PAIENTEB 1915 3. 86 1,1 09

SHEET 2 OF 2 F /r. n II n 1! II n u L l F 4r T" '/F T u n H n {I I II II I 77 .U2: i1 Lfi/ 1 s2 s4 s7 1 F NEAR SUPPORT F= CONCENTRATED LOAD LOADING W /ffXL'-'WL TOTAL WEIGHT DIAGRAM REACTIZ'JN I L FOR CONCENTRATED LOAD SHEAR DIAGRAM FIG. 8B

M WE L 4 I u 2 2 FL L 2 7 BENDING MOMENT l DlAGRAM FIE 86 FIG .9

CONTINUOUS SHEAR RESISTANT TIMBER GIRDER This invention is concerned with the field of building materials and more particularly a building material of the timber beam or girder class to be utilized in framing a building structure where a relatively long length of girder may be required to provide a span or bay of extended size.

It is advantageous in the building trade to employ timber beans or girders of a standard depth of approximately 16 inches and of varying lengths ranging up to from feet to 40 feet or longer.

Timber girder lengths greater than 20 feet are not often used as they are considered to be impractical for one reason or another. For example, with solid cross section beams, there is, in addition to cost considerations, the problem of weight which becomes excessively high in lengths as high as twenty feet and longer. A further problem arises where there is a need for cutting out access openings for receiving pipes, electrical conduits and other service lines since such access openings tend to weaken the beam undesirably.

In the trade, relatively long timber'lengths ranging above 20 feet are not always available and in order to provide timber girders in lengths ranging up to 20 feet and of suitably light weight character in which adequate strength could be maintained, it has been proposed in the art to provide fabricated girders and to combine dimension timber components such as 2 by 4s, 2 by 6s and 2 by 8s with reinforcing sections or panels as disclosed in U.S. Pat. No. 1,649,577, 3,079,649 and 3,106,752.

More recently, there has developed in the building trade a demand for timber girders of lengths ranging from 20 feet up to 28'and 30 feet, and in such timber girders of greater length, it is essential that there be provided access openings through which may be located pipe lines, electrical cable and other service facilities. However, even with fabricated girders of the class noted above, in lengths much beyond twenty feet, it is found that both shear and bending stresses may exceed safety limits and this is particularly the case where it is necessary to provide a plurality of access openings of the type noted at points along the girder.

It is a chief object of the present invention, therefore, to provide an improved timber girder construction in which dimension lumber and plywood webs are uniquely combined and solidly secured together by suitable areas of adhesive bonding to provide a fabricated girder body having access openings formed therein.

Another object of the invention is to devise a continuous shear timber girder having a 16 to 24 inch depth and ranging in length from 20 feet upwardly to 28 to 30 feet, in which light weight is combined with adequate bending and shear resistance strength.

Still another object is to devise a fabricated girder structure in which access openings are formed at areas of high shear stress and means are provided for exerting continuous shear stress resistance along the girder body and especially at those areas where the access openings occur.

Still another object of the invention is to devise a combination of dimension timber components and set of plywood webs in which substantial areas of adhesive bonding are utilized to provide a rigid interlocked girder structure throughout which shear stresses may be continuously transmitted in a uniformly distributed manner.

Having in mind these objectives, we have conceived of a continuous shear resistant timber girder of a fabricated construction which allows for concentrated loads to be applied anywhere along the girder within the limits of the bending and bearing strength of the girder, and at the same time, to have access openings in the structure and especially a series of from three to four openings at intervals spaced apart approximately four times the depth of the girder.

In this connection, we have devised a fabricated girder structure made up of a combination of dimension timber components, sets of plywood webs and layers of adhesive bonding material. This fabricated structure can be built up economically using standard sizes of dimension lumber and plywood webs to furnish strength and light-weight characteristics. In this fabricated girder structure, we provide shear stress resistance at the access opening areas. This shear resistance is obtained by providing shear resistance continuity through separated sets of webs in the fabricated girder structure. In this combination of parts, shear stress may be transmitted along the girder through separated sets of plywood webs and across access openings occurring between the webs. The shear forces are induced to flow from one web to a vertical stud located between adjacent web surfaces of the said web then from the vertical stud through a connecting diagonal stud extending across an access opening and then through another vertical stud to a succeeding plywood web.

We have found that in a: structure of the character described, concentrated loads may be distributed uniformly alonggirder lengths ranging from 20 feet up to 28 to 30 feet and as long as 40 feet, in some instances.

The nature of the invention and its other objects and novel features will be more fully understood and appreciated from the following description of a preferred embodiment of the invention selected for purposes of illustration and shown in the accompanying drawings, in which:

FIG. I is a plan view of the continuous shear timber girder construction of the invention;

FIG. 2 is a side elevation of the structure shown in FIG. 1;

FIG. 3 is an enlarged detail fragmentary view of a portion of the beam shown in FIG. 2 with web portions being broken away to indicate more clearly surfaces of adhesive bonding;

FIG. 4 is a cross section taken on the line 4-4 of FIG. 3;

FIG. 5 is a cross section taken on the line 5-5 of FIG. 3;

FIG. 6 is another planview of the girder illustrating diagrammatically flow of load forces along the girder;

FIG. 7 is a side elevational view of the girder further illustrating diagrammatically'flow of load forces;

FIG. 8'is a composite force diagram indicating both shear forces and bending forces, and

FIG. 9 is a composite plan view of a girder section indicating a set of webs separated from a flange component and further illustrating diagrammatically layers of adhesive material employed in securing the parts together.

The continuous shear resistant girder construction of the invention generally includes upper and lower flange members and sets of plywood webs arranged in longitudinally separated relationship to define access openings for pipes, electrical conduits and other service lines. The flanges are arranged one above another on vertical spacing studs occurring at separated points along the girder in positions such that web portions overlie outer surfaces of the studs.

An important feature of the girder construction is the provision of stress-transmitting studs arranged to extend diagonally from the bottom of a vertical stud in one set of webs to the top of a vertical stud in a succeeding set of webs. Inner surfaces of the plywood webs are solidly bonded at points of abutment with the flanges, vertical studs and overlapped ends of the diagonal studs by layers of adhesive bonding material to provide a solidly integrated component structure in which shear stresses are transmitted from one set of plywood webs to another in a uniformly distributed manner. Shear forces flow from one sets of webs to a vertical stud located between adjacent web surfaces of that set then from the vertical stud through a diagonal stud extending across an access opening and then through another vertical stud to a succeeding set of adjacent webs.

Considering our improved girder structure in greater detail, the Figures shown in the drawings illustrate a girder of approximately a 20 foot length in which are utilized five set of plywood webs and at either side of the center line of this girder are provided two access openings of approximately 9 inches width.

This girder is intended to be illustrative of box-like girder members of extended lengths ranging from 20 feet up to 28 to 30 feet, utilizing the same dimension lumber components and sets of plywood webs. It is pointed out that in a longer length, e.g. a length of 28 feet, two additional access openings can be obtained with no loss of strength. In 40-foot girders, six openings are possible.

As earlier discussed, a typical size of girder in lengths, as noted, has a depth of from 16 inches up to 24 inches, as this is a dimension highly convenient to work with in building construction. Since an important consideration is utilization of the least amount of building material possible with adequate strength provision, plywood in thicknesses of three-eighths of an inch and one-half inch are found to be most desirable. It will also be noted that the l6-inch depth girder allows for use of plywood sections cut out of a 4 by 8 standard size plywood sheet to provide three 16-inch width strips. These 16-inch widths of plywood may then be cut into desired. lengths for use along the sides of the girder construction shown in the drawings. The 24 inch plywood strips are readily obtained from two halves of a 4 by 8 foot plywood sheet.

In the drawings, arrow G denotes generally a preferred form of fabricated girder construction of the invention mounted on girder supports G, G1 and G2. Numerals 2 and 4 denote upper and lower flange components which may, for example, consist in continuous lengths of dimension lumber of the class commonly referred to as 2 by 6s, or separate lengths spliced together. The girder length represented in FIG. 1, as earlier noted, is intended to be illustrative of lengths ranging from 20 feet up to 30 feet or more. The flanges 2 and 4 are arranged flatwise one above another and have located therebetween vertical spacing studs as 6,

8, 10, l2, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32 and 34.

Fastening means such as nails N may be driven through the flanges into respective studs, as shown in FIGS. 3 and 4. A portion of the girder occurring at the left hand side of the center line CL of the girder G, as viewed in FIGS. 1 and 2, is shown on a somewhat larger scale in FIGS. 3, 4 and 5.

In accordance with the invention, we combine with the flanges and their vertical spacing studs a plurality of plywood webs especially arranged in sets of relatively long stretcher webs and relatively short bridging webs. As is best shown in FIG. 1 a first set is comprised by a stretcher web W1 and two bridging webs W4 and W5. A second set is comprised by stretcher web W2 and bridging webs W6 and W7. A third set is comprised by stretcher web W3 and bridging webs W8 and W9. Still another set is comprised by stretcher web W10 and bridging webs W11 and W12 and a final set is comprised by a stretcher web W14 and bridging webs W15 and W16. In a typical girder construction, as shown, the stretcher webs may have lengths of from 3 feet 3 inches, up to 3 feet 8 inches, and the bridging webs may have a length of 8 inches.

We arrange each of the sets in longitudinally spaced apart relationship to define a series of access openings A, A1, A2 and A3, through which may be received pipes, electrical conduits and other service lines. It is pointed out that in each set of webs, outer ends of a stretcher web and its respective bridging webs lie in common vertical planes which define the extent of the said access openings A, A1, A2 and A3.

In further combination with the multiple sets of stretcher webs and bridging webs, we provide stress transmitting timber components which may consist of stud members of the same dimensional size as the flanges earlier described, and each of these stud members is located so as to extend between adjacent sets of webs in diagonally disposed positions, as is most clearly shown in FIG. 3. The stud members are'denoted in the drawings by the numerals 40, 42, 44 and 46.

A highly important feature of the invention resides in utilizing a plurality of these stress-transmitting studs at the access openings and further in solidly securing opposite ends of each stud in a manner to create upper and lower trussed corner sections in each set of webs. Thuss each of the stress-transmiting members have opposite ends thereof secured along three sides in trussed relationship with adjacent flange and web sections. There is realized by reason of this arrangement a trussed corner construction having the capability to provide continuous shear resistance at all points along the girder. In this way, the maximum load sustaining strength of the-several components may be utilized with v shear stress being transmitted through the diagonal studs from point to point along the girder.

FIGS. 2 and 3illustrate the trussed corner structure most clearly, and FIG. 3 also indicates diagrammatically layers of adhesive bonding. As shown in FIG. 3, the diagonally disposed stress transmitting stud members 40, 42, 44 and 46 are cut with beveled ends which are fitted against adjacent surfaces of the upper and lower flanges 2 and 4. It will also be observed that extremities of the studs are located in abutting relation to adjacent vertical stud sides. It will be further noted that each end of a diagonal stud is overlapped for an appreciable part of its length by a stretcher web on one side and a bridging web on an opposite side. Finally it will be seen from an inspection of FIG. 2 that diagonally extending studs as 40 and 42, occurring on one side of the center line of LC of girder G are arranged in angularly opposed relation to studs 44 and 46 occurring at the other side of the center line of girder G.

In thus combining the various components to provide multiple trussed corner structures, it is found to be highly essential to fasten the various parts into a solidly secured integrated unit in order for it to be capable of transmitting required load forces without weakening within predetermined limits.

We have found that we may accomplish this by securing the girder components together with nailing and suitably placed layers of adhesive bonding material of the class commonly employed by those skilled in the art of gluing or bonding plywood and other wood components to one another. As is well known in this art, such adhesives are capable of sinking into the wood fibres of abutting wood surfaces to secure the parts together in an essentially welded relationship. The layers of adhesive, arranged in accordance with the invention, in effect, constitute bands of internal stiffening which greatly increase the ability of the components to transmit load forces without undesirable deflection or deformation.

The invention structure includes, therefore, an arrangement of component girder parts and the combination with this arrangement of parts of a purality of interconnected layers or bands of adhesive which extend throughout the girder structure in a unique angularly opposed relationship. These angularly disposed bands of adhesive are located so as to cooperate with one another and adjacent wood surfaces to provide resistance to shear and bending forces at those points along the girder where greatest increase in stiffening is required, namely, at or near the access openings.

In FIG. 3, a portion of stretcher web W2 has been broken away to indicate diagrammatically at either side of access opening A a horizontally extending layer of adhesive L combined with a vertical layer L1 occurring at right angles to layer L and intersecting each of the layers L and L1 at still another angle is a layer L2. Also intersecting layer L1 is a bottom layer L3. A similar set of angularly opposed layers of adhesive occur at an opposite side of the girder as viewed in FIGS. In FIG. 9, the webs are shown separated from flange 2, and the layers L, L1, L2 and L3 are indicated as they occur on the webs W2, W6 and W7 in relation to the flange 2. A similar set of angularly opposed layers of adhesive L, L1 L2, L3 are indicated on web W6. It will be apparent that these angularly disposed layers, in combination with the webs W2 and W6 and the adjacent flange and diagonal stud sections, function to provide a trussed upper corner to which the diagonal stud 40 is anchored for transmitting shear force therealong. The stretcher webs and bridging webs act as gussets to tie the diagonals at each end with the flue contacts to the vertical and horizontal timber.

Likewise layers of adhesive are located at the opposite end of web W2 and its midsection including the layers L4, L5 and L6 with the intersecting layer L6 occurring at a bottom corner section of the web W2 as shown in FIG. 3. Similar but primed references denote layers as they occur on the web W7 including layers L5, L, L3" and L6. There is thus provided a bottom trussed corner section as well as a top trussed corner section for each set of webs.

With the arrangement described, it will be observed that the layers of adhesive in a fully hardened and impregnated state constitute in effect thin bracket-like reinforcing elements occurring in angularly opposed disposition to one another in each set of webs. They act to withstand shear stress and bending stresses in a novel manner in rigidly welding together a horizontal stud section, a vertical stud section and a bracing diagonal stud section.

With this combination of welded parts and adhesive stiffening layers, it is found that shear stress may be selectively sustained in each of the various sets of webs described. Also with each set of webs and enclosed flange and stud portions, the maximum strength of the structural members is realized with very substantial reduction in material used and in the weight of the girder. A weight reduction to approximately half the weight of a solid section wood girder may, for example, be realized.

It will be understood that the structural combination described when subjected to the load forces commonly imposed upon a girder member in a building construction is required to sustain both shear and bending stresses. These stresses are exerted in accordance with well known shear and bending force diagrams for girders, as has been indicated diagrammatically in FIG. 8. As noted in FIG. 8, maximum bending stress F2 is indicated centrally of a girder while regions of highest shear stress Fl will occur along points between the center of the girder and its supported ends.

It will be observed that in supporting load forces of, for example, 55 pounds per square foot, commonly occurring in a building construction along an extended conventional girder, shear flexing may occur as well as secondary bending in the dimension timber members,

and these deformations will tend to increase with greater lengths of girder, and particularly at points at which the girder material is removed for access openings.

It has been determined from practical application of the girder of the invention in typical building construction use that with increased length up to 28 to 36 feet and more, shear stresses in the high shear stress zones may be sustained safely without any shear deflection occurring and without secondary bending at the top and bottom'flanges.

It is found that when load forces of the class indicated above are exerted on the fabricated girder structure of the invention, shear forces are caused to flow along the combined girder components in the manner diagrammatically illustrated in FIGS. 6 and 7. Thus, as shown in FIG. 6, wherever there occurs a high shear stress area in the girder, shear flow takes place in an adjacent set of plywood webs and flange portions. Shear flow is along a stretcher web, as suggested by the arrow S1, then from the stretcher web inwardly to a vertical stud as shown by arrow S2, then from the vertical stud through a diagonal stud as shown by arrow S3, then through another vertical stud at arrow S4 to another stretcher web as shown by arrow S5 at an opposite side of the girder.

From the foregoing description, it will be apparent that the fabricated girder and its multiple trussed corner section structures disclosed offers an outstanding advantage in that a plurality of access openings may be provided with adequate shear stress resistance being maintained at the access openings as well as at all points along the girder. As a result, improved distribution of load forces may be realized within limits of the bending strength of the girder. It is again pointed out that load forces imposed up to the maximum bending strength of the girder result in no shear flexing since the shear force is withstood by the web structure and its diagonal studs and trussed corners. It is also found that the girder of the invention will undergo no secondary bending in the top and bottom flanges, and as a result, the fabricated girder body behaves-like a solid cross beam without openings. These advantages are combined with light weight and ease of handling.

We claim:

1. An improved open box-type timber girder of the class employed in framing a building structure, being formed of an elongated length for spanning an open extended space in the building structure and for receiving load forces and containing shear and bending stresses without significant deformation, said timber girder comprising a light-weight body fabricated from dimension lumber components and plywood, said fabricated girder body including upper and lower dimension lumber flange members arranged flatwise one above another, vertically disposed spacing studs solidly secured between the flanges at separated points therealong, a

plurality of sets of plywood webs solidly secured at p-.

posite sides of the flange members in staggered overlapping relation to the vertical studs, said sets of webs having projecting edges which extend beyond adjacent vertical studs, said sets of plywood webs occurring in longitudinally separated relationship along the girder body to define a plurality of access openings through which may be received pipes, electrical conduits and other service lines, stress transmitting stud members extending across each of the access openings in a diagonally disposed position, opposite ends of each stud member being rigidly fastened between the said projecting members of adjacent sets of plywood webs, and said stress transmitting studs being of a length to extend from the bottom of a vertical stud in one set of webs to the top of a vertical stud in an adjacent set of webs to provide trussed corner sections in the girder at each access opening. I

2. A structure according to claim 1 in which the stress transmitting studs occur in groups of at least two studs and the groups are arranged in equal numbers at either side of the center of the girder, and studs in groups at one side of the girder center being arranged in angularly opposed relationship to studs in groups at the other side of the girder center.

3. A structure according to claim 2 in which inner surfaces of the plywood webs are solidly bonded at points of abutment with the flanges, vertical studs and overlapped ends of the diagonal studs by layers of adhesive bonding material to provide an integrated component structure in which shear stresses are transmitted from one set of plywood webs to a vertical stud located between adjacent web surfaces of the set then through a diagonal stud extending across an access opening and then through another vertical stud to a succeeding set of adjacent webs in a substantially uniformly distributed manner.

4. A structure according to claim 3 in which the said layers of adhesive bonding material include a plurality of spaced horizontal layers, vertical layers located between the horizontal layers at right angles thereto and diagonally disposed layers arranged to intersect the said horizontal layers and vertical layers at intervening angles to provide reinforcing bands of adhesive at each of the trussed corner sections of the girder.

5. A structure according to claim 1 in which the trussed corner sections occur at opposite ends of each set of webs in alternating top and bottom positions.

6. A structure according to claim 1 in which each set of webs includes a relatively long stretcher web and two relatively short bridging webs, said stretcher webs in successive sets alternating from one side to the other of the girder.

7. Animproved open box-type timber girder of the class employed in framing a building structure, being formed of an elongated length for spanning an open extended space in the building structure and for receiving load forces and containing shear and bending stresses without significant deformation, said timber girder comprising a light-weight body of substantial rectangular cross section fabricated from dimension timber frame components and plywood, said fabricated girder body including upper and lower dimension timber flanges arranged flatwise one above another, vertically disposed spacing studs solidly secured .between the flanges at separated points therealong, sets of plywood webs occurring in longitudinally separated relationship along the girder to define a plurality of access openings through which may be received pipes, electrical conduits and other service lines, and stress transmitting studs extending between adjacent sets of plywood webs, each of said sets of webs consisting in an elongated stretcher web secured to upper and lower flanges at one side thereof and a pair of relatively narrow separated bridging webs securedto the upper and lower flanges at an opposite side thereof, outer ends of each of said stretcher webs and respective bridging webs lying in common vertical planes which define the extent of the said access openings, said stress transmitting stud members positioned diagonally across each of the access openings, opposite extremities of each diagonally positioned stud member abutting against upper and lower flange surfaces and adjacent vertical studs,

each diagonally disposed stud further having extremities thereof lying in overlapping relationship with respective adjacent web surfaces, and said webs being solidly secured to abutting surfaces of the upper and lower flanges to the vertical studs, and to overlapped portions of the diagonally disposed studs by layers of adhesive bonding material to provide trussed corner sections at each access opening along which shear stress may flow continuously. 

1. An improved open box-type timber girder of the class employed in framing a building structure, being formed of an elongated length for spanning an open extended space in the building structure and for receiving load forces and containing shear and bending stresses without significant deformation, said timber girder comprising a light-weight body fabricated from dimension lumber components and plywood, said fabricated girder body including upper and lower dimension lumber flange members arranged flatwise one above another, vertically disposed spacing studs solidly secured between the flanges at separated points therealong, a plurality of sets of plywood webs solidly secured at opposite sides of the flange members in staggered overlapping relation to the vertical studs, said sets of webs having projecting edges which extend beyond adjacent vertical studs, said sets of plywood webs occurring in longitudInally separated relationship along the girder body to define a plurality of access openings through which may be received pipes, electrical conduits and other service lines, stress transmitting stud members extending across each of the access openings in a diagonally disposed position, opposite ends of each stud member being rigidly fastened between the said projecting members of adjacent sets of plywood webs, and said stress transmitting studs being of a length to extend from the bottom of a vertical stud in one set of webs to the top of a vertical stud in an adjacent set of webs to provide trussed corner sections in the girder at each access opening.
 2. A structure according to claim 1 in which the stress transmitting studs occur in groups of at least two studs and the groups are arranged in equal numbers at either side of the center of the girder, and studs in groups at one side of the girder center being arranged in angularly opposed relationship to studs in groups at the other side of the girder center.
 3. A structure according to claim 2 in which inner surfaces of the plywood webs are solidly bonded at points of abutment with the flanges, vertical studs and overlapped ends of the diagonal studs by layers of adhesive bonding material to provide an integrated component structure in which shear stresses are transmitted from one set of plywood webs to a vertical stud located between adjacent web surfaces of the set then through a diagonal stud extending across an access opening and then through another vertical stud to a succeeding set of adjacent webs in a substantially uniformly distributed manner.
 4. A structure according to claim 3 in which the said layers of adhesive bonding material include a plurality of spaced horizontal layers, vertical layers located between the horizontal layers at right angles thereto and diagonally disposed layers arranged to intersect the said horizontal layers and vertical layers at intervening angles to provide reinforcing bands of adhesive at each of the trussed corner sections of the girder.
 5. A structure according to claim 1 in which the trussed corner sections occur at opposite ends of each set of webs in alternating top and bottom positions.
 6. A structure according to claim 1 in which each set of webs includes a relatively long stretcher web and two relatively short bridging webs, said stretcher webs in successive sets alternating from one side to the other of the girder.
 7. An improved open box-type timber girder of the class employed in framing a building structure, being formed of an elongated length for spanning an open extended space in the building structure and for receiving load forces and containing shear and bending stresses without significant deformation, said timber girder comprising a light-weight body of substantial rectangular cross section fabricated from dimension timber frame components and plywood, said fabricated girder body including upper and lower dimension timber flanges arranged flatwise one above another, vertically disposed spacing studs solidly secured between the flanges at separated points therealong, sets of plywood webs occurring in longitudinally separated relationship along the girder to define a plurality of access openings through which may be received pipes, electrical conduits and other service lines, and stress transmitting studs extending between adjacent sets of plywood webs, each of said sets of webs consisting in an elongated stretcher web secured to upper and lower flanges at one side thereof and a pair of relatively narrow separated bridging webs secured to the upper and lower flanges at an opposite side thereof, outer ends of each of said stretcher webs and respective bridging webs lying in common vertical planes which define the extent of the said access openings, said stress transmitting stud members positioned diagonally across each of the access openings, opposite extremities of each diagonally positioned stud member abutting against upper and lower flange surfaces and adJacent vertical studs, each diagonally disposed stud further having extremities thereof lying in overlapping relationship with respective adjacent web surfaces, and said webs being solidly secured to abutting surfaces of the upper and lower flanges to the vertical studs, and to overlapped portions of the diagonally disposed studs by layers of adhesive bonding material to provide trussed corner sections at each access opening along which shear stress may flow continuously. 